Question

The radii of two circles are 13 cm and 6cm respectively the radius of the circle which has circumference equal to sum of which has circumference of two circles is

Answer 1

2πr + 2πr = 2 πr

2*22/7*13 + 2 * 22/7*6 = 2*22/7 *r

common 2*22/7 (13+6 ) = 2*22/7 *r

by cancelling 2 *22/7 both sides

                            r = 19

       hope it helps you